CARDIOMEMS, which is owned by St. Jude Medical, is a new FDA-approved device used for monitoring pulmonary artery pressures in patients with a history of systolic or diastolic heart failure and prior heart failure hospitalization within one year. The data from the device is transmitted wirelessly to a secure website and reviewed by health professionals. The sensor is very durable as it does not require a battery and does not have any moving parts. The sensor allows volume status of millions of patients worldwide to be managed more accurately and precisely. Various implementations of the CARDIOMEMS device are described in several U.S. patents, including U.S. Pat. Nos. 6,855,115, 7,966,886, and 8,353,841, which are incorporated by references in their entireties.
To deliver the CARDIOMEMS device to the left pulmonary artery, a guide wire and catheter are engaged in the left pulmonary artery using fluoroscopy, followed by obtaining an angiography of the left pulmonary branches. The branch of interest is located, and a picture of it is saved into the catheterization lab monitor. Then, the branch of interest is accessed with a delivery catheter over the wire. The device is deployed based on the assumption that the location has not changed.
For example, as described in U.S. Pat. No. 8,353,841, the CARDIOMEMS device may be delivered and deployed in its intended location in an artery using the delivery assembly shown in FIG. 1. The delivery assembly includes a main lumen 202 through which a core wire 204 is disposed and a secondary lumen having four sections 224A-224D through which a tether wire 211 is disposed. The tether wire 211 enters and exits the secondary lumen sections 224A-224D to attach wire loops 255, 235 of the CARDIOMEMS device 251 to the delivery assembly. The core wire 204 is fixed to the main lumen 202 and provides columnar stiffness to the delivery assembly, which facilitates advancement of the delivery assembly through the vasculature and prevents buckling of the delivery assembly when the tether wire is pulled proximally during deployment of the device 251. The main lumen 202 also includes a guide wire aperture 212 through which guide wire 210 extends into the main lumen 202. The delivery apparatus may be moved along the guide wire 210 through the artery in which the device 251 is to be deployed.
The lung is a very dynamic organ. For example, a wire within the left pulmonary artery may move 3 inches axially as the patient breathes. Therefore, establishing landmarks for delivering devices within the pulmonary artery can be very difficult. If the device is deployed distally of the branch of interest, the pressure waves are dampened. And, if the device is deployed proximally of the branch of interest, there is an increased risk that the device will dislodge in the main pulmonary artery, where it cannot be retrieved.
Accordingly, there is a need for an improved system and method for delivering an implantable device within a patient.